A mild hybrid vehicle includes an engine configured for propulsion and an electric motor configured to assist the engine. One type of mild hybrid vehicle includes a belt-driven starter generator (BSG) unit. The BSG unit utilizes the electric motor to selectively provide power to a crankshaft of the engine (e.g., via a belt). The BSG also replaces a conventional alternator and thus could be used for start-stop of the engine, power assist, and/or regenerative braking, as well as powering other vehicle components. The BSG unit is powered by a battery pack, such as a 48 volt battery pack.
Because the electric motor and battery pack are part of the BSG unit, the battery pack is located in a high temperature environment proximate the engine and therefore requires cooling. Conventional cooling systems capable of handling such cooling needs, such as a heating, ventilation, and air conditioning (HVAC) system or other refrigerant-based system, however, are too large to meet the small packing size requirements or today's vehicles. Therefore, while such thermal management systems work for their intended purpose, there remains a need for improvement in the relevant art.